Power element



June 15, 1965 J. s. FRElsMuTH 3,188,857

POWER ELEMENT Filed 00TH 15, 1962 l 7 y i A TTORNE YS United States Patent O 3,183,367 PWER ELEMENT John S. Freisrnuth, Arlington Heights, iii., assigner to Sterling Automotive Manufacturing Company, Eli-r Grove Village, Iii., a corporation of illinois Filed st. 15, 1962, Ser. No. 230,647 8 Claims. (Cl. 73--363.3)

This invention relates to new and useful improvements in force-transmitting devices and is more particularly directed to thermal elements of the type operated by pressure changes of a contained pressure-producing material and which are adapted for use in valves, switches, controls and the like.

Heretofo-re, diiiiculty has been encountered in the design of such devices or thermal elements, particularly in the design of sealing means for a diaphragm forming a part thereof which contains vthe pressure-producing material.

An object of the present invention is to provide a new .and improved thermal element.

Ano-ther object of the present invention is to provide a thermal element having new and improved sealing means forming a part thereof.

Still another object of the present invention is to provide a therm-ostatic thermal element or device having an expansible material therein adapted for causing movement of a sealing diaphragm.

A further object of the present invention is t-o provide la diaphragm of preformed rubber or elastomeric material for use in a thermal element or device.

`A still further object of the present invention is to provide a diaphragm of rubber or other elastomeric material which cooperates with other parts of the thermal element to prevent both leakage of the pressure-producing material .and introduction of the ambient heat producing medium into the thermal element during opera- .tion thereof.

Other objects, features and advantages of the present invention will become readily apparent from a careful consideration of the following detailed description, when considered in conjunction with the accompanying drawings, illustrating preferred embodiments of the presen-t invention, wherein like referenece numerals and characters refer t-o like and corresponding parts throughout th-e several views, and wherein:

FIG. 1 is an enlarged view in vertical section of a thermal element construction in accordance with the principles of the present invention.

FIG. 2 is an exploded view in section of the thermal element of lFIG. 1 illustrating one form of a force-transmitting member found useful in the practice of the present invention.

FIG. 3 is an enlarged view in vertical section of a second embodiment of a thermal element constructed in accordance with the present invention.

FIG. 4 is a view in elevation of another form of a force-transmitting member `found useful in the practice of the presen-t invention.

Referring to FIGS. 1 and 2, there is shown a thermal element, generally indicated by the numeral 6, which comprises a cup, container or casing 7 constructed of heat-conductive material, such las brass, a bored plunger or pist-on guide member 8, a diaphragm member 2i), a

Fatertted .irme l5, 15165 plug member A1G, and a piston or plunger 11 reciprocable in the bore Sii of the guide membe-r 3.

The casing 7 is of general cylindrical configuration :and is provided with a sleeve rim 12. The guide member 8 is of stepped external construction and includes an upper section 13 which is of generally cylindrical configuration :and which is rjoined to a frusto-conical or truncated conical portion 14 which carries an outturned annular end flange 15 which is sized to be received by a rim sleeve 12 provided on the casing 7. The rim 12 and the casing 7 are of generally cylindrical configuration, and the rim 12 is lbent over to form an annular locking ilange 112:1 which secures the flange 15 of the guide member S .to the casing 7, to assemble the guide member and casing. During such assembly, the diaphragm member 2t? is squeezed between the casing .and guide member in a reces-s 37 formed in the lower surface 3S of the guide member (FIG. 2).

The casing '7 defines a chamber 16 (FIG. 2) which is of a diameter greater than the diameter of the bore 3@ and is provided to receive a body of expansible and contractible temperature-respon'sive material l17, which may be a material, such as paraiiin or the thermal materials Adisclosed in US. Patent No. 1,259,846. The chamber A16 and bore 30 are coaxial and the casing 7 has a cylindrical sidewall 7a and a bottom wall 7b. The chamber .16 has :an open upper end indicated `by the numeral 19.

`Spanning and closing the upper end 19 of the chamber 16 is the diaphragm member 2t) of elastomeric or other rubber-like material. Referring to FIG. 2, the diaphragm 2o i-s premolded and comprises a central body section 21 and an annular peripheral sealing bead 22. The body 21 is premolded to have a uniform cross-section-al dimension or thickness, and the bead 22 is premolded so that it has an upper portion 23 extending above the upper surface 2e of the body section 21 and a similar lower portion 2S extending below the lower surface `26 of lthe body `section 21.

The rim 12 of the casing 7 has an internal shoulder or surface 27 which is provided with an annular sealing groove 28 for receiving the lower portion 25 of the bead 22 o-f the diaphragm 2i). Similarly, the flange 15 of the guide member 8 is provided with an annular sealing gro-ove 29 in :alignment with the groove 2S. The groove 2-9 receives the upper portion 23 of the bead 22 of the diaphragm 20.

The guide member and casing are in axial alignment, when assembled, and the guide member 8 is provided with the bore 3Q of lesser diameter than the chamber 16 .and is sized to receive the piston or plunger 11. The bore 33t? is stepped to provide an annular shoulder 31 which is tapered in cross-section. Above the sh-oulder 311, the bore section 36a, dened by the upper portion 13 of the guide member S, is cir-cular and is of a iirst diameter. The bore 3i) diverges at an angle adjacent one end thereof to provide a truste-conical bore section Siib which defines the shoulder 31 :and joins the bore section 30a with `a cylindrical bore section Stic which is circular and which is of a second diameter greater than the diameter of the guide section 36u.

The plug 1d is inserted in the bore 30 from the recessed end of the ange 15 and -is sized to the -bore length so that it extends from the recess 37 of the guide member S to a location in Ithe tirst diameter portion of the plunger 1-1 above the tapered section `30h of the bore '30 as appears in FIG. 1.

Referring to FIG. 4, the plug may be 'a cylinder of elastomeric material of a predetermined diameter so that, when it is inserted in the Ibore 30, in theV manner abovedescribed, the plug is squeezed to conform to the contour of the bore 30, as clearly appears in FIG. 1. The plug 10, as appears in FIG. 2, may -be premolded to a shape which includes a bott-om portion 40 Awrhchpis cylindrical Vand of a length predetermined in accordance Iwith the length Yof the bore 30, a frusto-conical portion -41 sized tothe diverging portion of the shoulder 31 of the bore 30 and a second cylindrical porti-on 42 of a lesser diameter thanthe portion 40 and sized lto the upper portion of the bore.

It will be appreciated that the plug 10 (FIG. 2), or

10' (FIG. 4), has an exterior diameter which will assure that theplug is snugly tted'in the bore 30 and in the position ysh-own in FIG. 1.

At one end, the plunger -11 is bottomed-against the flat upper sun-face of the plug 10 or 10', and the plug is bottomed on the upper surface of the diaphragm inwardly ofthe bead 22. 'Y

In assembling the 'thermal element 6, the temperature responsive material 17 is rst introduced into the chamber 16 Adet'ined by the casing 7, asappears in FIG.' 2, and then the -diaphragm 20 disposed over the .material 17 -with the bead -bottomportion seated'in the groove 28 formedY and will assume the shape of the bore 30, as viewed in FIG. 1. v i f YThe guide member, with the plug 10 or l10 in the bore 30, is placed in the rim 112 in such a manner that the upper portion 23 of the bead 22 seats in the annular groove 29 of the guide member and the recess 37 receives the diaphragm body inwardly of the bead 2'2.V The diaphragm body portion l 21 is of greater vcross-sectional dimension than the depth of the recess =37v lfor purposes set forth hereinafter. Y f

With the parts thus assembled, the marginal ilange 12a ofthe rim 12 is bent over and inwardly to clamp the guide 8 and casing? together as appears inVFIG. 1 to complete the assemblyof the Y,thermal element. In so clamping the casing vand guide member, the diaphragm body; 21 iS squeezed between the inner Iupperl Surface '49 of the casingvrirn 12 and the inner lower surface 50ct the recess of the guide member to deform the diaphragm and 'form areduced portion or neck 32 connecting vthe cad 22 to the remainder of body 21 which rspans'the open end yof the chamber 16. Y j

. The body portion 21'of the` diaphragm which spansV the material 17 is ofgenerallyuniformlhickness after the thermal Velement is assembled `and Iwhen the temperature of the material 17 is Ibelow its expansion level. The bottom wall 33 of the,V guide member which is located inwardly of the groove 29, Vit will be observed, extends radially inwardly a greater `distance than the side wall 34 of the casing 7 and, thus, overlies more of the diaphragm body 21 than the sidewall 34. As the material 17 eX- pan-ds afterl its expansive temperature level has lbeen reached, the body 21 of the diaphragm will .he caused to move upwardly into the bore '30' of Ythe guide member and will dene, in cross-section, Van inverted cup-shaped portion (not shown). In changing tothe cup-shaped form, the diaphragm body 21 acts against the plug l10 which, in the assembled thermal element, is seated against the top Y If the plugl() (FIG. 2) is employed, the preshaped plug will also bepress-tted into the bore 4 surface of the diaphragm. The diaphragm tends to force Y the plug 10 upwardly for movement of a part thereof Vc, the height, H, of the plug inthe smaller diameter portion 30a of the bore must increase. in accordance with the general formula V :AI-I. Therefore, the length, H, of the portion of the plug 10 in the smaller diameter section 36a of the bore will increase as the pl-ug moves in the bore upwardly in this manner. The plug -10 or 10 imparts motion to the pistongll kwhich acts against an external force, such as a spring (not shown), to actuate a switch or valve (not shown). The spring (not shown) may be a -compression spring which is adapted to return the plunger to its inoperative position vshown in FIG. 1, when the expansible-.material 17 contracts as a result ofa reductionin the temperature of the material 17 below 'the expansion temperature limitof the material. p

It will be appreciated that the expansion of the 'material 17 will cause deformation of the diaphragm b'ody 21, and, in so deforrning, the thickness of the portion of the diaphragm lbody 21 spanning the material 17lwi1l bereduced. Moreover, thesedeformation forces `have a tendency to exert a force'onjthe diaphragm body'to pull the body inwardly Ifrom between the guide member and casing. However, compression of the bead 22 in the corresponding grooves 28 and V29 prevents such inward movement of the diaphragm and maintains the sealingeffect thereof onfthe casing cham-ber during distortion of the body portion of the diaphragm by the expansionrof the material 17. The flange 8 and shoulder 27 which contact outwardly of the .grooves 28 and 29 cooperate with the bead 22 and grooves 28 and 29 to prevent leaking of the ambient lheat producing medium into the chamber of the casing. Movement, therefore, of theV diaphragm during operation of the thermal element is'limited thereby tothe area underlying the plug 10, and, thus, the yaforementioned movement of the diaphragm is increased and is concentrated in the area underlying the plug 10 vso that the-movement of the plunger and opening of the valve will occur within a short time afterinitiation of movement of the diaphragm.

In. the embodiment of the present invent-ion appearing in FIG, 3, the casing 7 is provided lwith an outturned annular ange 52 Vinstead of a rim, such as the yrim 12 appearing in FIG. 1. yA power element assembly clamping member 54 is provided which is a separate sleeve and which is turned inward at both ends, as at 56 and 58 vto assemble the casing? and guide member 8. AThe bead 22 of the diaphragm 20 -isk compressedin the grooves 28 and 2,9, the plug 10 or '10v is employed as is the stepped -bore 30 of the guide member, as clearly Aappears in FIG. 3f The operation of this assemblyis similar tothe operation ofthe assemblyof'FIG. 1, above described. v

It is preferable to provide arecess 60 in thecasing'7 which communicates with the casing 1chamber at the open end thereof. This recess 60 is 'preferably tapered in crossinvention will become readily apparent t'o those've'rsed inl `medium into the casing 7.

scope of the contribution Although various minorr modifications of the present.

the art, it should be understood 4that whatis'intended to be covered by the rpatentrwarrgmted hereon are all such embodiments as reasonably' and properlycome within the to the art hereby made.

p Iclaim: v v l 1. A thermal element comprising: a heat conductive Basses? casing having an axial chamber With an open end, the transverse end wall surface of the casing adjacent the open end of the chamber having a sealing groove therein formed inwardly of the outer marginal edge of said end wall surface, a guide member having an axial bore of lesser diameter than the diameter of the chamber and having a transverse end wall surface overlying and extending radially inwardly toward the longitudinal axis of the casing a distance greater than the said end wall of the casing, said end wall surface of the guide member having a counterbore recess formed therein radially inwardly of the outer marginal edges of each of said end wall surfaces, said end wall surface of the guide member having a sealing groove formed in the counterbore recess thereof which is in axial alignment with said sealing groove of the casing; an elastic diaphragm spanning the open end of the chamber and extending between said end wall surfaces of said casing and guide member, said diaphragm including a pre-formed body portion disposed in the counterbore recess of the guide member, said body portion being of uniform cross-sectional dimension which is greater than the depth dimension of said counterbore, and an elastic bead carried at the outer marginal edge of said diaphragm body in both of said sealing grooves, a plunger in the bore of the guide member movably responsive to movement of said diaphragm, and means for clamping said casing and guide member to assemble the thermal element by contacting said end wall surfaces of the casing and guide member outwardly of the bead, whereby said bead is squeezed in said grooves and a portion of the diaphragm body located inwardly of the bead is squeezed between the counterbore portion of the guide member and the end wall surface of the casing to thereby seal the open end of the chamber of the casing.

2. The thermal element of claim 1 wherein said clamping means is a ring.

3. The thermal element of claim 2 wherein said ring is a sleeve which is formed integrally with the casing and which receives the counterbored end wall of the guide member, the sleeve having the outer edge portion thereof turned to clamp the guide member to the casing.

4. The thermal element of claim 2 wherein the ring is a separate member receiving both the casing and the guide member, and wherein opposite ends of the ring are turned to clamp both the guide member and the casing.

5. A thermal element comprising: a heat conductive casing having an axial chamber with an open end, the transverse end wall surface of the casing adjacent the open end of the chamber having a sealing groove therein formed inwardly of the outer marginal edge of said end wall surface, a guide member having an axial bore and an abutting end surface with a sealing groove formed therein which is spaced inwardly of the marginal edge of the abutting end surface and which is in axial alignment with the sealing groove of the casing, said surface of the guide member also having a counterbore therein concentric with the bore; an elastic diaphragm spanning the open end of the chamber and including a pre-formed body disposed in the counterbore, said body portion being of uniform crosssectional dimension and of greater thickness than the depth of the counterbore, an elastic bead carried by the body at the outer marginal edge thereof, said bead being disposed lin both of said sealing grooves, a plunger in the bore of the guide member movably responsive to movement of said diaphragm, and means for clamping said casing and guide member to contact said abutting end surfaces outwardly of the grooves, whereby said head is squeezed in said grooves and the portion of the diaphragm body located inwardly of the bead is squeezed between said abutting end surfaces to thereby seal the open end of the chamber.

6. A thermal element comprising: a heat conductive casing defining a chamber having an open end for receiving a heat responsive expansible material and having an abutting end wall surface with a sealing groove therein spaced inwardly of the marginal edge of said surface, a guide member having an axial bore and an abutting surface with a sealing groove therein spaced inwardly of the marginal edge of said surface of the guide member and in axial alignment with the sealing groove of the casing, a counterbore in said surface of the guide member concentric with the bore, a movable piston in the bore of the guide member, a resilient diaphragm having a pre-formed body portion of uniform cross-sectional dimension disposed in the counterbore, said body portion being of greater cross-sectional dimension than the depth of the counterbore, a bead having a greater cross-sectional dimension than said body portion carried by the body portion of the diaphragm at the marginal outer edge thereof, said bead being disposed in both of said sealing grooves, and means for clamping said guide member and casing to contact said abutting surfaces of the casing and guide member together with a predetermined applied force to assembly said thermal element, whereby said bead is squeezed in said grooves and a portion of the diaphragm located inwardly of the bead and between the abutting surfaces is squeezed between said surfaces to seal the open end of said casing chamber.

'7. A thermal element comprising: a heat conductive casing defining a chamber having an open end for receiving a heat responsive expansible material, a radial outturned flange on the casing adjacent the open end of the chamber having an abutting surface with a sealing groove therein spaced inwardly of the outer edge of the flange and carrying a clamping sleeve spaced outwardly of the sealing groove, a guide member in the sleeve having an axial bore and a recess concentric with the bore in a first surface thereof, said first surface having a sealing groove formed in the recessed por-tion thereof, inwardly of the outer edge of the first surface, and in axial alignment with the sealing groove of the casing, a movable plunger in the bore, a diaphragm having a pre-formed body portion of uniform thickness greater than the depth of the counterbore disposed in the counterbore of the guide member in contact with the plunger and closing the open end of the chamber, said diaphragm carrying a marginal sealing bead of greater thickness than the body portion, said sealing bead being disposed in the sealing grooves of both the guide member and casing, whereby clamping of said ring with a predetermined applied force to assemble said casing and guide member will squeeze the sealing bead in said sealing grooves and squeeze the portion of the diaphragm body disposed between said abutting surface of the casing iiange and the first surface of the guide member to thereby seal the chamber.

8. A thermal element comprising: a heat conductive casing defining a chamber having an open end for receiving a heat responsive expansible material, a radial outturned flange on the casing adjacent the open end of the chamber, said flange having an abutting surface with a sealing groove therein spaced inwardly of the outer edge of the ange, a clamping ring carried by the casing outwardly of said groove, a guide member having a bore and carrying an axially extending sleeve in the ring, said sleeve having an abutting surface in surface-to-surface contact with the abutting surface of the casing flange, said sleeve defining with a first surface of the guide member a counterbore concentric with said bore, said first surface of the guide member having a sealing groove therein spaced inwardly of the sleeve and in axial alignment with the sealing groove of the casing, a movable plunger in the bore, a diaphragm having a pre-formed body portion of uniform cross-sectional dimension greater than the depth of the counterbore disposed in the counterbore of the guide member, in Contact with the plunger, and closing the open end of the casing, said diaphragm carrying at the marginal edge thereof a sealing bead which is of greater thickness than the said body portion and which is disposed in the sealing grooves of boththe casing and the guide member, f References'Cite'd by the Examiner" whereby clamping lof said ring with a predetermined ap- "UNITED STATES, PATENTS plied force Itro assemble said casing and saidguide member ing grooves and of that part off the body portion ofthe Y diaphragm iWhih is inwardly ofjthe bead'andis located VFOREIGN PATENTS between thefabu'ttng surfaces of the guide fmember rand 531 280 1/41 GreatBmain.

the casing -ange to therebyseal theVK open endY of said 10 easing chamber," ISAAC LISANN, Primary Exwrniner. 

1. A THERMAL ELEMENT COMPRISING: A HEAT CONDUCTIVE CASING HAVING AN AXIAL CHAMBER WITH AN OPEN END, THE TRANSVERSE END WALL SURFACE OF THE CASING ADJACENT THE OPEN END OF THE CHAMBER HAVING A SEALING GROOVE THEREIN FORMED INWARDLY OF THE OUTER MARGINAL EDGE OF SAID END WALL SURFACE, A GUIDE MEMBER HAVING AN AXIAL BORE OF LESSER DIAMETER THAN THE DIAMETER OF THE CHAMBER AND HAVING A TRANSVERSE END WALL SURFACE OVERLYING AND EXTENDING RADIALLY INWARDLY TOWARD THE LONGITUDINAL AXIS OF THE CASING A DISTANCE GREATER THAN THE SAID END WALL OF THE CASING, SAID END WALL SURFACE OF THE GUIDE MEMBER HAVING A COUNTERBORE RECESS FORMED THEREIN RADIALLY INWARDLY OF THE OUTER MARGINAL EDGES OF EACH OF SAID END WALL SURFACES, SAID END WALL SURFACE OF THE GUIDE MEMBER HAVING A SEALING GROOVE FORMED IN THE COUNTERBORE RECESS THEREOF WHICH IS IN AXIAL ALIGNMENT WITH SAID SEALING GROOVE OF THE CASING; AN ELASTIC DIAPHRAGM SPANNING THE OPEN END OF THE CHAMBER AND EXTENDING BETWEEN SAID END WALL SURFACES OF SAID CASING AND GUIDE MEMBER, SAID DIAPHRAGM INCLUDING A PRE-FORMED BODY PORTION DISPOSED IN THE COUNTERBORE RECESS OF THE GUIDE MEMBER, SAID BODY PORTION BEING OF UNIFORM CROSS-SECTIONAL DIMENSION WHICH IS GREATER THAN THE DEPTH DIMENSION OF SAID COUNTERBORE, AND AN ELASTIC BEAD CARRIED AT THE OUTER MARGINAL EDGE OF SAID DIAPHRAGM BODY IN BOTH OF SAID SEALING GROOVES, A PLUNGER IN THE BORE OF THE GUIDE MEMBER MOVABLY RESPONSIVE TO MOVEMENT OF SAID DIAPHRAGM, AND MEANS FOR CLAMPING SAID CASING AND GUIDE MEMBER TO ASSEMBLE THE THERMAL ELEMENT BY CONTACTING SAID END WALL SURFACES OF THE CASING AND GUIDE MEMBER OUTWARDLY OF THE BEAD, WHEREBY SAID BEAD IS SQUEEZED IN SAID GROOVES AND A PORTION OF THE DIAPHRAGM BODY LOCATED INWARDLY OF THE BEAD IS SQUEEZED BETWEEN THE COUNTERBORE PORTION OF THE GUIDE MEMBER AND THE END WALL SURFACE OF THE CASING TO THEREBY SEAL THE OPEN END OF THE CHAMBER OF THE CASING. 